Electro-optical device for the photo-polymerization of composite material

ABSTRACT

An electro-optical device for the photo-polymerization of composite material, used in particular in the dental field includes a light source ( 2 ) which is defined by an LED or a group of LEDs. It has an electrical power supply including a battery ( 4 ) which is associated with a direct current/direct current converter device ( 7 ) commonly known as a DC/DC converter, passive elements ( 3 ) for the evacuation of heat, and a central management unit ( 5 ) for operating parameters of the light source for the definition of a determined photo-polymerization energy profile.

The present invention has for its object an electro-optical device forthe photo-polymerization of composite materials, particularly applicablein the dental field.

The composite materials used in the dental art are generally based on aphoto-polymerizable resin of which the molecular structure istransformed under the effect of a light radiation of a given wavelengthas a function of the capacity of absorption of the material used. Inthis way, during polymerization, this radiation activates the photoinitiators of the material for an exposure time calculated as a functionof the energy of this radiation in order to avoid too great anoverheating of the tissues surrounding the zone of treatment.

It should be observed that the parameters of the radiation, wavelength,intensity, exposure time, depend, of course, on the particularcomposition of each composite, but also on its colour and its thickness.A darker composite of greater mass will necessitate for itsphoto-polymerization a radiation of greater intensity. This is what iscalled the parameters of polymerization. In order to allow these factorsto act in optimal manner, i.e. in manner invariable during the exposuretime and for a time sufficiently long for a practitioner to be able touse them during his sessions of care without dangerous interruption, nosufficiently reliable solution has been proposed.

Photo-polymerization devices responding to the description which hasbeen made hereinbefore are already known, which use electro-luminescentdiodes, usually called LEDs, capable of emitting, often, a radiation ofwave-lengths included between 380 and 510 nm. For example, such devicescomprise a power card, a cooling system, a source of light and opticalmeans for orienting and emitting the light energy produced by saidsource in the direction of the zone to be illuminated (or clinicalsite). These electronic means are for example in the form of a supplycard, of the type with supply by linear regulation, the current of theLEDs being defined by polarization resistance, and of an activeventilation system (ventilator or by Peltier effect) or a passive one(ceramic card).

In the end, these heretofore known apparatus are adapted to emit aradiation of a defined profile without possibility for the operator tobe certain that its power is stable and obliging him to support thenoxious effects of the cooling ventilator or the debatable efficiency ofthe passive cooling systems mentioned above. In fact, the only parameteron which an action is possible with precision is the time ofillumination. Such devices thus hardly present any guarantee of use andare of limited application.

As light source in this type of apparatus, use is made, for example, ofmercury vapour lamps which present the drawback of emitting in theultra-violet spectrum, which is dangerous for the patients' eyes andbuccal mucous membrane. Such lamps use sources of supply requiring highstarting currents and voltages, and cooling systems most often based onventilators and therefore with pulsed air or possibly, for the mostpowerful ones, based on water circulation and radiators. Other devicesuse halogen lamps which have the drawback of presenting a low lumen/wattratio and a high heat dissipation with respect to the light energyproduced, this making it necessary to limit the rise of the power inorder to obtain greater intensities. Such lamps use supply sources whoseyield is without comparison with respect to the useful power, andcooling systems likewise based on pulsed air.

Other devices are equipped with lasers, but the light beams that theygenerate correspond to a monochromatic light which, due to its reducedwavelength spectrum, can, there again, polymerize only well definedcomposites. Such lamps use complex supply sources and cooling systemswith pulsed air or circulation of water. Moreover, the lasers areexpensive apparatus which, in addition, present high maintenance andimplementation costs.

Devices are also known which employ spaced electrodes subjected todifferences in electrical potential adapted to produce an electric arcthrough a partially ionized gas at high temperature. Such systemsemploy, in combination, an infrared filter placed immediately in frontof the source and allowing a light spectrum of emission included between400 and 800 nm to be obtained. A low-pass filter makes it possible thento fix the high cut-off frequency of the filter at about 515 nm. Suchlamps use supply sources requiring starting voltages of severalkilovolts and cooling systems employing pulsed air for the less powerfuland circulation of water for the others.

However, in these devices, the filtering system does not make itpossible to increase, without danger, the light power of the source, asthe light energy absorbed by the biological tissues may lead to theirdestruction in the case of considerable rise in temperature. Inaddition, the energy profile, which represents the variations of thelight intensity emitted in the course of time, cannot be modified.

This consequently excludes any possibility of adapting it to compositematerials of different colours, for example.

Photo-polymerizing devices also exist, which use plasma energy and havean isolated selective emission zone thanks to more or less complexfiltrations. A document FR-98 01243 describes such an apparatus. Suchlamps use supply sources which, there again, necessitate startingvoltages of several kilovolts and cooling systems employing pulsed airor circulation of water.

It should be noted that such devices present the particularity ofallowing highly caloric radiations to pass in zones beyond the 1200 nm.This has the consequence of dangerously raising the temperature at themoment of polymerization. Furthermore, such devices requirehigh-performance cooling systems which are of high cost and weight.

Photo-polymerization devices are also known, for example by documentsEP-A-0 880 945, JP-A-9010238, U.S. Pat. No. 5,634,711, PCT/AU97/00207,of which the light source is defined by LEDs. In fact, it is question ofa plurality of blue LEDs disposed on a support deck perpendicularly tothe interior of the body of the apparatus. At the front of this deck ofLED diodes are located means for concentrating the radiations emittedand for orienting them in the direction of a wage guide of which thedistal end projects this concentrated radiation on the surface to betreated. This device may take the shape of a gun connected to an outsideelectrical energy supply. These lamps use as supply sources resistorsfor determining the polarization current of the LEDs. Contrarily to thedevices described previously, the need for cooling is less. In effect,the conversion “electrical energy” into “light energy” is effected witha very good yield and when the LEDs are used at their nominalcharacteristic, the heat dissipation generally does not necessitateactive cooling means. In the case of use with photo-polymerization, itis sought to obtain the greatest power of the diodes, this beingpossible by causing them to function with a current greater than thatnormally provided.

If no precaution is taken, this increase of the current generates anoverheating of the diodes which modifies their electricalcharacteristics, and a lowering of the power emitted. In that case, theresult inverse to that desired is obtained. The common mastery of thethermal behaviour and of the electrical supply are necessary to obtainthe highest power.

In all the cases cited, and more particularly those relating to the LEDsources, the apparatus receives conventional supply systems which areunstable in time, and the general behaviour is very sensitive to therise in temperature. The manufacturers of LEDs have noted in particularthat a rise in temperature of 40° may bring about a modification of thecurrent transmitted and therefore a lowering of power of close to 50%.

All the assemblies which have been proposed solve the problem onlypartially or oblige the user to use conventional cooling systems whichare noisy and have to be connected to the mains, thus considerablylimiting his freedom to work. Moreover, it in no way solves the problemraised, insofar as it is hardly possible to modify the intensity of thisradiation, its density per surface unit or the number of sequences ofirradiation, for all that. Finally, the application of the apparatusdescribed in these documents is, there again, limited to a determinedtime, the operator having only the possibility of managing, to a lesserextent, the time of illumination and of recharging the batteries inorder to be sure that he is respecting and guaranteeing the thickness ofthe material to be photo-polymerized.

In the end, although it is possible, through the known techniques, toplay on the exposure in primary manner, i.e. to reduce or increase theexposure time, it is impossible, in real time today, to do so with alarge time or power scale. In effect, no dynamic variation is possiblewith the present-day apparatus.

The present invention has for its object to overcome the afore-mentioneddrawbacks by proposing an electro-optical device for thephoto-polymerization of composite materials, applicable in particular inthe dental domain allowing an independent, stable and adjustable supplyof energy, comprising an optimized and stable electronic system, a lightsource based on LED not requiring active ventilation, as well as thermalmeans for orienting and evacuating the heat energy produced by saidsource in order to ensure a reliable polymerization during the clinicalact and in time.

Thus the invention concerns an electro-optical device for thephoto-polymerization of composite materials, applicable in particular inthe dental field, of the type comprising a light source which is definedby an LED or a group of LEDs, and which is essentially characterized inthat it comprises electronic power supply means consisting of a batterywhich is associated with a direct current/direct current converterdevice, commonly known as a DC/DC converter, passive means for theevacuation of heat, as well as a central management unit for theoperating parameters of the light source for the definition of adetermined photo-polymerization energy profile.

The DC/DC converter, of which the output is variable, makes it possibleto adjust without resistance the polarization current by limitation ofthe direct voltage, with the result that this makes it possible tosecuritize the quality of the care given thanks to a stability of thepower emitted by monitoring the heat behaviour, a long life of thebattery, several days, thanks to a reduced consumption of electricity,the maintenance of the power emitted whatever the state of charge of thebattery, up to complete discharge of the latter.

According to an additional characteristic of the device according to theinvention, it comprises a power circuit making it possible to supplyeach LED or LED group at a predefined value by cyclic ratio modulation.

According to another additional characteristic of the device accordingto the invention, it comprises a device for correcting the thermal driftof the LEDs.

According to another additional characteristic of the device accordingto the invention, the passive heat evacuation means comprises an LEDsupporting electronic card whose design includes metallic tracks fortransfer of the heat from the base of each of the LEDs towards theperiphery of the card.

According to another additional characteristic of the device accordingto the invention, the passive heat evacuation means comprise aheat-conducting material disposed around the casing of each of the LEDsin order to remove the maximum of calories from each of the diodes andto transfer them to the periphery of the card.

According to another additional characteristic of the device accordingto the invention, the passive heat evacuation means comprise a metallicradiator connected to the card by a heat-transmission paste or glue, anda thermal joint between said card and said radiator towards a metalpiece with high thermal inertia serving as receptacle for calories andas support for the optical assemblies necessary for the system.

According to another additional characteristic of the device accordingto the invention, the passive heat evacuation means comprise atemperature sensor embedded in the thermal joint and making it possibleto have, in real time, the temperature level of the optical assembly.

The optical systems necessary for conducting the light so as to maintainthe power emitted in respect of the energy needs forphoto-polymerization as a function of the characteristics of thecomposite material to be photo-polymerized.

According to a particular form of embodiment of the device according tothe invention, the heat evacuation means comprise one or the other ofthe following characteristics, individually or in combination:

-   -   an electronic card on which the LEDs are welded, the welding        spots being connected to electrical tracks of large dimension        having a very good heat conductivity, said electronic card is        pierced with metallized thermal wells which conduct the calories        as rapidly as possible towards the rear face of the card and        therefore far from the LEDs.    -   heat-conducting products placed in contact with the peripheral        walls of the diodes which are not in contact with the card        itself. These products may be pasty and deposited between the        diodes then hardened thereafter, they may equally well be solid        and cut to the exact shape of the location of the diodes        maintained intimately with the diodes by means of a good heat        conductor (paste or glue).    -   a metallic radiator at the rear of the card, connected to said        card by a paste or thermal glue, serving to recover the calories        coming from the thermal wells traversing the card.    -   the elements are thermally connected by paste or thermal glue to        a metallic piece of high thermal inertia which also serves as        support for the optical elements. This latter piece serves to        pump the calories rapidly and to store them temporarily when the        lamp is lit and restores them more slowly by conduction or        convection towards the assembly of the system when the lamp is        not used.    -   a temperature detection system allowing the supply to be cut        when the storage capacity of the metallic piece is attained.        According to an additional characteristic of the device        according to the invention, the electronic supply means        comprise:    -   a circuit for control by shift register and cyclic ratio        modulation making it possible to select and modulate the power        of emission of each LED group,    -   a high-yield DC/DC converter supplying the control circuit by        lowering the battery voltage,    -   a direct polarization of the electro-luminescent diodes by the        output of the DC/DC converter by using the internal resistance        of the diodes,    -   a system for adjusting said polarization voltage in order to        vary the supply current of the diodes and consequently the        optical power,    -   an automatic correction of this polarization voltage by thermal        servo-control in order to have available a constant output        power.

The high-yield DC/DC converter makes it possible to reduce the primarycurrent issuing from the battery thus prolonging its life duration andits autonomy. Moreover, the use of this DC/DC converter makes itpossible to dispense with the variations of voltages due to thevariations of the level of charge of the battery.

The light source advantageously comprises a means for measuring thetemperature adapted to detect the maximum storage of temperaturecompatible with the stability of optical power emitted.

This monitoring system advantageously functions between two minimum andmaximum levels functioning in hysteresis in order to limit the currentin the diodes in the event of dysfunction of the heat regulation systemand thus reduce overheating.

The battery is preferably of the Li ion battery type provided with atemperature sensor in order to securitize the apparatus.

The battery is advantageously of the hybrid Ion battery type making itpossible to manage the charge level and to display it on an LCD screen.

From among the means for maintaining the power of the card, it will beobserved that the device for monitoring and stabilizing the power ispiloted by servo-control, this enabling this power to be maintained atthe desired value.

The present invention advantageously comprises a potentiometer forpreadjusting the power setting, this making it possible to adjust anindustrial production to the same known value thanks to an individualadjustment of each apparatus.

Of course, such a solution enables other functionalities to beenvisaged, such as remote adjustment, tele-diagnosis or remotemaintenance of the power of the photo-polymerization device according tothe invention, or the remote adjustment via Internet, or the adjustmentby the user or the upgrading of the power in after sales service.

The advantages arising out of the present invention consist in that thedevice is applicable virtually universally, as its use is not simplylimited to a determined type of LED lamp. Insofar as it is possible toadopt any photo-polymerization energy profile, this device is, in fact,capable of being adapted to the particularities of each of these lamps.The operator is therefore no longer obliged to use a particular LEDrange to polymerize the composite materials, apart from the fact that hecan modify the operating conditions of his photo-polymerization devicehimself by taking into account his own experience, but also theconditions of use of the material. Finally, a correct adjustment of thepower and its thermal monitoring enables the needs expressed in thisdomain to be answered.

Other objects and advantages of the present invention will appear in thefollowing description which relates to a form of embodiment given by wayof indicative and non-limiting example.

Understanding of this description will be facilitated by studying theaccompanying drawings, in which:

FIG. 1 schematically shows the device forming the subject matter of thepresent invention, its body appearing in transparency.

FIG. 2 schematically shows LED diode supporting discs orientedperpendicularly to the longitudinal axis of the body of the device anddistributed about this axis.

FIG. 3 schematically shows FIG. 2 in transverse section.

FIG. 4 schematically shows the device and an electrical charging supportadapted thereto.

FIG. 5 corresponds to a schematic representation of the device includingthe part defining the power supply and the means employed.

FIG. 6 is a view similar to FIG. 5, where the systems of adjustmentappear.

FIG. 7 schematically illustrates the device forming the subject matterof the invention, equipped with means for remote acquisition, of theenergy type and/or other data in its memory.

FIG. 8 is a more detailed plan of the electronic diagram of the device.

FIG. 9 is a graph illustrating the intensity or the density ofillumination as a function of time, of the wave length and of the powerof emission or of the number of emitting diodes.

As is shown in these Figures, the present invention relates to a device1 for photo-polymerization of composite materials which will find moreparticular interest in the dental domain.

This device 1 comprises a body 10 inside which its principal constituentelements are positioned. Thus, this device 1 comprises a light source 2in the form of an optical cone and preferably comprisingelectro-luminescent diodes 20, called LEDs, capable of emitting a lightradiation of a determined wave length or in a defined wave lengthspectrum.

By way of example shown in FIGS. 2 and 3, the LED diodes 20 aredistributed on a support disc 21 extending perpendicularly to thelongitudinal axis of the body 10.

The device 1 also comprises heat evacuation means 3 for orienting andemitting the heat energy produced by the light source 2 in the directionof a zone corresponding to an evacuation which does not reduce theefficiency of the device.

As visible in this FIG. 1, such heat evacuation means 3 may beconstituted by a heat evacuation guide 30 located in the front part ofthe body 10.

It will be observed more particularly that the present invention is inno way limited to such thermal or opto-electronic means. In effect, theymay also take the form of one or more evacuation channels, even that ofa paste, known by the person skilled in the art familiar with the domainof heat guides and which, in the present application, presents theadvantage of promoting the conduction of the calories generated, andtherefore making it possible to conserve the same power emitted. Insofaras one of the particularities of the present invention consists inoptimizing the reaction of photo-polymerization, this reduction of theenergy drop of the light emission is very important.

In addition, these heat evacuation means 3 may be in the form of atrack, each track being in register with a LED 20, this allowing a heatevacuation for each of the LEDs 20 in selective manner on the support.The device is thus transformed into a controllable and individualelimination means. As has already been set forth hereinabove, thisparticularity allows a controllable optimization of the heat evacuation.

Furthermore, the source of energy 4, which consists in FIG. 1 in abattery, and the optical means may be integrated in an interchangeablepart of the body 10, thanks to appropriate connection means, thisfacilitating replacement thereof in the case of ageing of the lightsource 2, without counting the fact that the latter may be substitutedby a more or less powerful energy source, for example comprising more orfewer LED diodes 20. In addition, the removability of the energy source4 makes it possible to replace the latter rapidly in order to replace itin the event of failure.

The device further comprises a central unit 5 for managing the operationof the light source 2 for the definition of a determinedphoto-polymerization energy profile.

In this way, thanks to an autonomous electrical supply, therefore one ormore batteries 4, preferably of the rechargeable type and/or means 40for connection to the mains supplying electricity to a dwelling, shownin FIG. 4, the central unit 5 controls, via a power card 6, theoperation of the light source 2 in determined sequences of illuminationand with defined powers.

In FIG. 4, a charging support 11 has been shown which is moreparticularly adapted to receive the device 1 in the course of rechargingof the batteries 4 integrated in the latter.

As for the LED diodes 20, they are preferably subdivided into elementarymodules 22, as is schematically shown in FIG. 8, each comprising anumber of LED diodes 20 which is identical or not, and supplied byregulation circuits. These latter make it possible, through the centralunit 5, to supply the LED diodes 20 of each of these elementary modules22 at well defined powers.

Furthermore, the energy source 4 is associated with a directcurrent/direct current converter device 7, commonly called a DC/DCconverter, equipped with an adjustment potentiometer 70, and in the formof a module.

As is more particularly visible in FIG. 9, the DC/DC module 7, just likea transformer in alternating mode, cuts the battery voltage and smoothesit in order to obtain a perfectly constant output voltage whatever thevoltage issuing from the battery 4. An adjustment device makes itpossible to adjust a basic output voltage which will then be modulatedas a function of the information issuing from the temperature sensor.

Furthermore, the power card 6 comprises a circuit 60 for control byshift register and cyclic ratio modulation, making it possible to selectand modulate the power of emission of each group of LEDs 20.

In order to optimize the integration of these elements in a portable,therefore not cumbersome, unit, the assembly of the shift registers andcurrent regulation circuits may be grouped in an ASIC.

It should be noted in addition that the interest of this concept ofshift registers and of regulation circuits for each module 22 of LEDdiodes 20, resides in the fact that it is not limited in terms ofmaximum luminosity, since a plurality of these modules 22 of LED diodes20 may be placed in cascade.

In order to respond further to this preoccupation of integration, theASIC may be mounted on the opposite face or the disc or discs 21 withrespect to the LED diodes 20 or modules 22 of diodes.

FIG. 8 shows a diagram of the device in greater detail. The latter thuscomprises in particular a charger unit BC, a direct current supply DC, amicro-controller MC connected to a memory M, to a library B and to anoperator interface IO.

As shown in FIG. 8, the DC/DC module 7 is directly connected to thebattery 4 of which it will lower the voltage to take it to the desiredpower reference value, this power reference being corrected in real timeby the central unit card 5 as a function of the information issuing froma temperature sensor CT.

FIG. 8 graphically represents the supply power of each module 22 of LEDdiodes 20 for a determined energy profile, in the course of a definedradiation sequence. While FIG. 9 represents the intensity or the densityof illumination as a function of time of the wave length and of thepower of emission or of the number of emitting diodes.

This representation also makes it possible to demonstrate that, by usingdifferent cyclic ratios, the central unit 5 has the possibility ofmodulating the power of the LEDs therefore the power of the radiationemitted.

According to the invention, the device 1 thus comprises, in combination,means for adjusting one or more of the operating parameters of the lightpower, namely:

-   -   the intensity of illumination    -   the cyclic ratio    -   and/or the density of illumination per surface unit;    -   the monitoring of the temperature    -   and/or duration of each of these sequences so as to adapt the        polymerization energy profile as a function of the        characteristics of the photo-polymerization lamp.

These means consist of means for selecting in a memory connected to saidcentral unit 5, a determined energy profile from a plurality of profilespre-recorded in this memory and/or a datum, there again, from aplurality having been previously recorded in said memory, relative toone or more of the adjustable parameters.

In this way, by way of example, in the DC/DC card 7, a chopping of thereference voltage will make it possible to vary the power of each groupof diodes 20.

The operator may still have the choice, through a menu, betweendifferent pre-established energy powers. It should be noted that suchselection means enable the operator to adjust this power.

A combination of these different types of adjustment means may, ofcourse, be envisaged.

The device advantageously also comprises adjustment means, there againin the form of a potentiometer and/or of a touch screen and/or any otheracquisition means, particularly remote ones, for the programmation ofthe memory connected to the central unit, precisely in order to recordtherein different energy values and/or different data relative to theadjustable parameters.

It should be noted that these adjustment means may employ means fordownloading data, particularly through a micro-computer 8 via an RS232Cinterface 50, as shown in FIG. 5, in order to download, for example, newenergy adjustments through a network of Internet type. These downloadingmeans may also take the form of a modem, either directly integrated inthe device, or in the loading support 11 to which reference has beenmade hereinabove in the description.

According to another form of embodiment, these power adjustment meansmay be in the form of bar code reading means CB.

It is also possible to use a memory in the form of a smart card,preferably of the programmable type, the device 1 comprising anappropriate reader. There again, this smart card reader may be found atthe level of the loading support 11, in particular if it is desired tolighten the tool part that the user must manipulate.

Once again, it will be observed that the device 1 may comprise acombination of these different forms of embodiment of the acquisitionmeans described hereinabove.

The particular purpose of the means for adjusting one or more of theparameters of the power of the light source is to intervene further onthe density of illumination per surface unit, as indicated hereinabove.In effect, it is possible to adjust this density of illumination byintervening, particularly via the regulation circuits, on the number ofLED diodes supplied at the level of each elementary module and/or on theintensity of their supply in the course of a photo-polymerizationreaction.

It follows from the foregoing description that the present inventionresponds perfectly to the problem raised in that it brings a realresponse to the modification of power and to the thermal elevation ofthe LED lamps as present-day devices for the photo-polymerization ofdifferent types of composite materials. Taking everything into account,the device according to the invention gives the user the possibility ofadjusting the operating conditions of his apparatus as he wishes, withthe result that he is no longer limited, as was often the case in thepast, to the use of a determined power and to a drop of this power intime.

1. Electro-optical device for the photo-polymerization of compositematerials, applicable in particular in the dental field, of the typecomprising a light source (2) which is defined by an LED (20) or a groupof LEDs, characterized in that it comprises electronic power supplymeans consisting of a battery (4) which is associated with a directcurrent/direct current converter device (7), commonly known as a DC/DCconverter, passive means (3) for the evacuation of heat, as well as acentral management unit (5) for the operating parameters of the lightsource for the definition of a determined photo-polymerization energyprofile.
 2. Device according to claim 1, characterized in that itcomprises a power circuit making it possible to supply each LED (20) orgroup of LEDs (20) to a predefined value by cyclic ratio modulation. 3.Device according to claim 1, characterized in that it comprises a devicefor correcting the thermal drift of the LEDs.
 4. Device according toclaim 1, characterized in that the passive heat evacuation meanscomprises an LED supporting electronic card whose design includesmetallic tracks for transfer of the heat from the base of each of theLEDs towards the periphery of the card.
 5. Device according to claim 1,characterized in that the passive heat evacuation means comprise aheat-conducting material disposed around the casing of each of the LEDsin order to remove the maximum of calories from each of the diodes andto transfer them to the periphery of the card.
 6. Device according toclaim 1, characterized in that the passive heat evacuation meanscomprise a metallic radiator connected to the card by aheat-transmission paste or glue, and a thermal joint between said cardand said radiator towards a metal piece with high thermal inertiaserving as receptacle for calories and as support for the opticalassemblies necessary for the system.
 7. Device according to claim 6,characterized in that the passive heat evacuation means comprise atemperature sensor embedded in the thermal joint and making it possibleto have, in real time, the temperature level of the optical assembly. 8.Device according to claim 1, characterized in that the heat evacuationmeans comprise independently or in combination: an electronic card onwhich the LEDs are welded, the welding spots being connected toelectrical tracks of large dimension having a very good heatconductivity. Said electronic card is pierced with metallized thermalwells which conduct the calories as rapidly as possible towards the rearface of the card and therefore far from the LEDs. heat-conductingproducts placed in contact with the peripheral walls of the diodes whichare not in contact with the card itself. These products may be pasty anddeposited between the diodes then hardened thereafter. They may equallywell be solid and cut to the exact shape of the location of the diodesmaintained intimately with the diodes by means of a good heat conductor(paste or glue). a metallic radiator at the rear of the card, connectedto said card by a paste or thermal glue, serving to recover the caloriescoming from the thermal wells traversing the card. all these elementsare thermally connected by paste or thermal glue to a metallic piece ofhigh thermal inertia which also serves as support for the opticalelements. This latter piece serves to pump the calories rapidly and tostore them temporarily when the lamp is lit and restores them moreslowly by conduction or convection towards the assembly of the systemwhen the lamp is not used. a temperature detection system allowing thesupply to be cut when the storage capacity of the metallic piece isattained.
 9. Device according to claim 1, characterized in that theelectronic supply means comprise: a circuit for control by shiftregister and cyclic ratio modulation making it possible to select andmodulate the power of emission of each LED group, a high-yield DC/DCconverter supplying the control circuit by lowering the battery voltage,a direct polarization of the electro-luminescent diodes by the output ofthe DC/DC converter by using the internal resistance of the diodes, asystem for adjusting said polarization voltage in order to vary thesupply current of the diodes and consequently the optical power, anautomatic correction of this polarization voltage by thermalservo-control in order to have available a constant output power. 10.Device according to claim 1, characterized in that the light sourcecomprises a means for measuring the temperature adapted to detect themaximum storage of temperature compatible with the stability of opticalpower emitted.
 11. Device according to claim 1, characterized in thatthe battery is of the Li ion battery type provided with a temperaturesensor in order to securitize the apparatus.
 12. Device according toclaim 1, characterized in that the battery is of the hybrid Ion batterytype making it possible to manage the charge level and to display it onan LCD screen.
 13. Device according to claim 1, characterized in that itcomprises a potentiometer for readjustment of the power reference makingit possible to adjust an industrial production to the same known valuethanks to an individual adjustment of each apparatus.
 14. Deviceaccording to claim 2, characterized in that it comprises a device forcorrecting the thermal drift of the LEDs.